Culprit No. 1: High-fat foods. Anything that is deep-fried; is made with a lot of oil,butter, cream or cheese; features fatty meats; or is otherwise high in fat will "slow down motility in the upper gut, which can trigger reflux (aka heartburn) and gas," explains Dr. Charlene Prather, a gastroenterologist and a professor of internal medicine at Saint Louis University.

At the same time, high-fat foods "stimulate the colon," which can aggravate IBS, she says. "So for anyone who has gastrointestinal problems, we recommend a low-fat diet."

What else can tick off your tummy? "Everybody's different. There are certain foods that some people say don't agree with them, and those foods may not be a problem for other people," says Dr. Richard Desi, a gastroenterologist at Mercy Medical Center in Baltimore.

With that said, some foods tend to be especially problematic for people who are prone to heartburn, gas or IBS. If you're one of them, here are some of the most common foods upsetting your stomach -- and how to cope.

Heartburn

What triggers heartburn differs from person to person, but common culprits (in addition to high-fat foods) include chocolate, peppermint and coffee, all of which relax the lower esophageal sphincter, which keeps stomach contents from flowing upward and causing heartburn, says Prather. In addition, acidic foods, such as citrus fruits andjuices,tomatoes and sodas, as well as spicy foods, can cause a burning sensation in an already irritated esophagus.

How to cope: "If you're predisposed to reflux and these things cause you trouble, avoid them," advises Prather. If that doesn't help -- or if you find you have to give up too many of the foods you love -- talk to your doctor, who may recommend medication. Keep in mind, though, that these foods don't bother all heartburn sufferers. So if your stomach can handle a food, there's no need to avoid it.

Gas

Cruciferous vegetables, such as cabbage, broccoli and cauliflower, as well as beans and carbonated beverages, can produce gas in the gut. And if you eat quickly, you're more likely to swallow air, which contributes to gas, notes Desi. In addition, chewing gum or consuming foods that contain sugar alcohols -- such as sorbitol, xylitol or mannitol -- as well as foods with high amounts of fructose can produce gas in people who are sensitive to these ingredients. Sorbitol, xylitol and mannitol are artificial sweeteners commonly found in sugar-free sweets, including gum, hard candies, ice creams, cookies and puddings. Fructose is the natural sugar in fruits and vegetables and may occur in particularly high concentrations in fruit juices and "naturally sweetened" products. (Check the labels for "fruit juice concentrate,""high-fructose corn syrup" and plain "fructose.")

How to cope: Cooking cruciferous veggies tends to make them less gas-provoking than eating them raw, notes Prather. Or, you can take a supplement that contains alpha-galactosidase, a digestive enzyme that breaks down starches from legumes and cruciferous vegetables, thereby preventing gas. Sometimes, simply eating smaller amounts of these foods can help you avoid filling up with air.

Irritable Bowel Syndrome (IBS)

"With IBS, the foods are all over the map in terms of what triggers it and what doesn't," says Desi. That's because with IBS, the gut is just generally reactive to food, and it's hard to identify which foods might be problematic from day to day. Avoiding high-fat foods is a good idea. And some people with IBS have an element of lactose intolerance, which can make them sensitive to dairy products. Be aware, though, that with lactose intolerance, "it can vary from day to day and depend on how much lactose you're consuming," says Desi.

How to cope: Eating smaller, low-fat meals can help reduce IBS symptoms. If you have a problem with lactose, you can limit or avoid dairy products or take lactase supplements to help you digest them. (Yogurt may be easier to tolerate because of the live, active cultures they contain, adds Prather.) If you have the constipation variety of IBS, slowly increase your intake of fiber-rich foods (such as fruits, vegetables and whole grains) and drink plenty of water, advises Prather.

By taking precautions to deal properly with foods that may be upsetting your stomach, you'll be able to enjoy them while you're eating them -- and afterwards.

Stacey Colinohas written for The Washington Post'shealth section and many national magazines, including Newsweek, Real Simple, Woman's Day, SELF, Marie Claire, Cosmopolitan, Glamour, Parenting, Sports Illustrated and Ladies' Home Journal.

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